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flowering
Generally when orchid blooms, inflorescence is
formed that may produce single to many flowers, sequentially or in mass. For sympodials,
inflorescence can arise from terminal (ancient)
and/or abaxial (modern). Some even arise from the
rhizome, as in some Bulbophyllum. Monopodials can never
have terminal inflorescence. Inflorescence can be
erect, arching or pendulous. Many orchids have
flower buds that are rotated 180° before opening, a
mechanism known as resupination. Not all orchid
flowers resupinate. To trace resupination, one can
simply observe the longitudinal line of an ovary of
a flower and detect whether there was a twisting
before. Otherwise as a rule of thumb, assuming the
upright configuration of an orchid flower is to have
the lip at the bottom of the flower, an erect
inflorescence with upright flowers are resupinated,
while pendulous inflorescence with upright flowers
are non-resupinated.
Flowering is an exciting topic; different orchids
require different triggers for flowering.
Inflorescence may whither away after one flowering,
or continue on for some numbers of flowering. For the
former, a longer time may be needed (not in all
cases) for flowering because it includes time for
inflorescence development. For the latter,
inflorescence initiation may be dependent or
independent of triggers. Inflorescence development
may not necessarily follow by flowering. When the
right trigger arrives, the inflorescence can produce
bloom in a short time.
One of the most popular triggers for flowering is
the drop of temperature brought by rainfall, after
which many orchids will bloom. These include those from
Dendrobium, Flickingeria, Thrixspermum,
etc. The
most popular example is Dendrobium crumenatum,
or commonly known as the ‘pigeon orchid’, that will
bloom exactly 9 days after a torrential rain from
its dormant inflorescence that seems lifeless. Its
flowers are fragrant but only last for a day or
less. Flowers of Thrixspermum and Flickingeria also last for less
than a day. Another example is Dendrobium
anosmum that responds to low temperature brought by
rainfall but its flowers can last for several days. |
